dr bob

Might be time to get a new one. The old one has pretty much been squeezed of all its extra capacity by time and mineral clogs. Pull the end tanks and see how many rows are plugged with calcium deposits, along with the oil cooler section. There's enough extra designed-in capacity for folks to run them at reasonable loads when flow is restricted by 25 years worth of internal deposits. Your SC motor is too much for the fraction of total radiator capacity you have left. With the radiator removed. you might be able to look into the bottom of the driver's side tank with a flashlight and a mirror and see what you are facing for flow restrictions.

Get one of 928 Int'ls aluminum replacements. You'll be just a bit happier I suspect.

Tampa 928s

Good point!!